OXIDATION OF NAPHTHENOAROMATIC AND METHYL-SUBSTITUTED AROMATIC-COMPOUNDS BY NAPHTHALENE 1,2-DIOXYGENASE

Oxidation of acenaphthene, acenaphthylene, and fluorene was examined w ith recombinant strain Pseudomonas aeruginosa PAO1(pRE695) expressing naphthalene dioxygenase genes cloned from plasmid NAH7, Acenaphthene u nderwent monooxygenation to 1-acenaphthenol with subsequent conversion to 1-acenaphthenone and cis- and trans-acenaphthene-1,2-diols, while acenaphthylene was dioxygenated to give cis-acenaphthene-1,2-diol. Non specific dehydrogenase activities present in the host strain led to th e conversion of both of the acenaphthene-1,2-diols to 1,2-acenaphthoqu inone. The latter was oxidized spontaneously to naphthalene-1,8-dicarb oxylic acid, No aromatic ring dioxygenation products were detected fro m acenaphthene and acenaphthylene. Mixed monooxygenase and dioxygenase actions of naphthalene dioxygenase on fluorene yielded products of be nzylic 9-monooxygenation, aromatic ring dioxygenation, or both, The ac tion of naphthalene dioxygenase on a variety of methyl-substituted aro matic compounds, including 1,2,4-trimethylbenzene and isomers of dimet hylnaphthalene, resulted in the formation of benzylic alcohols, i.e., methyl group monooxygenation products, which were subsequently convert ed to the corresponding carboxylic acids by dehydrogenase(s) in the ho st strain, Benzylic monooxygenation of methyl groups was strongly pred ominant over aromatic ring dioxygenation and essentially nonspecific w ith respect to the substitution pattern of the aromatic substrates, In addition to monooxygenating benzylic methyl and methylene groups, nap hthalene dioxygenase behaved as a sulfoxygenase, catalyzing monooxygen ation of the sulfur heteroatom of 3-methylbenzothiophene.